| 摘要 |
A swimming pool has a recirculating pump and filter. A drain line from the high pressure side of the pump drains excess water through a hydraulically operated drain valve remote from the pool. A long narrow tube from the high pressure line drains into the pool at a float valve. When the level of water in the pool is too high, the float valve opens, and pressure in the tube drops. Pressure in the tube operates the drain valve, opening the drain valve when the level is high and the pressure is low, and closing the drain valve when the level is not high, the float valve is closed and the pressure is high. The invention may be alternatively practiced with a drain valve that is opened by a high control pressure using a float valve that closes when the pool level is high. A timer controlled valve in the tube prevents opening the drain valve during preselected times when the pool is occupied.
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